This is good to know. I plan on getting one of the S-700-12 and I like the idea of being able to add them together as needed. If I were to use three of them, then I would run them on 220v. A single 30A 120V is possible but not practical. Of course you could run three 120v circuits to them, but by the time you did that it would be cheaper and easier to run one run of 230v.From the Mfg. Three S-700-12's would require 30 amps on 120 V or 15 amps 220 V.